This invention relates to a manikin for practising artificial respiration by the mouth-to-mouth or mouth-to-nose method, said manikin comprising an inflatable element simulating a lung (in the following referred to as the lung), an element simulating a chest (in the following referred to as the chest) and a hollow element simulating a head (in the following referred to as the head), said head having a cavity containing a replaceable inflatable bag having an air inlet which is airtightly connected with a replaceable element simulating a mouth and nose, the cavity in the head being connected with the lung through an air duct.
Danish patent specification No. 137.206 describes a manikin of the above mentioned type.
The replaceable inflatable bag of the prior art manikin is preferbly made from a non-elastic material and it has such a shape that it collapses when the lung returns to its non-inflated state which occurs when the user removes his mouth from the nose and mouth element of the manikin and allows the pressure within the bag to return to atmospheric pressure. Concurrently with the collapse of the bag, air which during the inflation of the bag was introduced into the cavity of the head and further into the lung through the air duct flows back to the cavity in the head.
If the secondary air system, i.e. that part of the cavity of the head which surrounds the bag, the air duct and the lung, leaks--and in practise leakages often occur--air will pass from the secondary air system to the surround atmosphere during the inflation of the lung.
Therefore, the bag does not collapse completely when the lung has returned to its non-inflated state.
Consequently, a reduced amount of air will be introduced into the air duct and the lung during a new inflation of the bag and the amount of air introduced will decrease further during each subsequent cycle.
Due to the accumulating amounts of air in the bag even minor leakages in the secondary air system will cause such changes during each practising cycle that the manikin gradually ceases to function anatomically correct and in a reproducible manner.
It has been attempted to use a bag of an elastic material, e.g. a rubber balloon, but in that case the simulation of the resistance against inflation of the lung and the chest rather depends on the properties of the rubber balloon than on the properties of the lung, and consequently the use of the manikin becomes less realistic. Furthermore, such a rubber balloon has to meet high quality requirements which make the balloon expensive and increase the costs of practising. Thus, for hygienic reasons and in particular in order to reduce the risk of spreading of infectious matter a new balloon has to be inserted when a new person starts practising.